TITLE:   GCN CIRCULAR
NUMBER:  3124
SUBJECT: GRB050319: BR optical photometry
DATE:    05/03/20 06:17:12 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

D. Sharapov, M. Ibrahimov,  R. Karimov, B. Kahharov (UBAI), A.Pozanenko
(IKI), V.Rumyantsev (CrAO),  G.Beskin (SAO) report:

We observed afterglow candidate of Swift GRB050319  (Rykoff et al.  GCN
3116, Krimm et al. GCN 3117)  with 1.5m telescope of Mt.Maidanak
high-altitude observatory. BR-band images  were taken in two sets of
observation on (UT) March 19, 17:14 --17:58  and 19:18 -- 21:45.  We confirm
a fading afterglow (Yoshioka et al. GCN 3120). Preliminary  photometry
against of USNO-B1.0 Catalog is following:

Mean time  Exposure Filter  Mag.
(UT)         (s)

Mar.19 17:28  900   B  20.85
Mar.19 17:31 1500   R  20.12
Mar.19 20:17 1800   B  21.29
Mar.19 20:16 4800   R  20.17

with typical magnitude error of less than 0.10.
B-R at the two epochs marginally indicate color variation which is not
typical for this phase of afterglow.

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